border-1px($color)
	position:relative
	&:after
		display:block
		position:absolute
		left:0
		bottom:0
		width:100%
		border-top:1px solid $color
		content:''	
		
border-none()
  &:after
		display:none
		
bg-image($url)
	background-image:url($url + "@2x.png")
	@media (-webkit-min-device-pixel-ratio: 3),(min-device-pixel-ratio: 3)
		background-image:url($url + "@3x.png")